eMedicine Specialties > Neurosurgery > Trauma

Acute Nerve Injury: Treatment

Author: Idan Sharon, MD, Consulting Staff, Departments of Neurology and Psychiatry, Cornell New York Methodist Hospital; Private Practice
Coauthor(s): Chaim I Fishfeld, DO, General Surgeon, South Nassau Community Hospital
Contributor Information and Disclosures

Updated: Sep 17, 2009

Treatment

Medical Therapy

The goal of treatment is to return function to the damaged nerve and, at minimum, to improve the quality of life of patients. Not only is the nerve treated, but exogenous sources of nerve injury also are treated. Bone dislocation with neurological deficit requires prompt anatomical reduction to prevent irreversible nerve necrosis.¹  

Imaging work-up of developmental lesions that involves the axial skeleton most frequently involves plain radiographs, followed by CT for assessment of bony matrix and MRI for evaluation of intrinsic spinal cord parenchymal changes and potential neural compression. With some lesions, bony scintigraphy or PET scanning may be helpful to assess for metabolic injury.²⁴

The use of analgesics can help patients control pain from nerve injuries.¹³ Meloxicam (Mobic) administered over 2-4 weeks has shown to be an effective medication.

The second- and third-generation anticonvulsant drugs (AEDs) that have shown promise in several studies in the past few years include oxcarbazepine (Trileptal), zonisamide (Zonegran), topiramate (Topamax), levetiracetam (Keppra), and lamotrigine (Lamictal). These results may be due to their GABA effects. These agents are most helpful clinically in the signs and symptoms of radiculopathic and neuropathic pains and paresthesias.

Antivirals and steroids help to decrease endoneurial edema, an etiology of nerve injury.¹⁷ Hyperbaric oxygen (HBO) is an approved adjunctive treatment for acute traumatic ischemic reperfusion injury.¹⁷ HBO decreases endoneurial edema and pressure and vascular compromise of the vasa nervorum.¹⁷ Ciliary neurotrophic factor (CNTF) enhances motor neuron survival both in vivo and in vitro. Because CNTF continues to undergo research, its treatment benefits remain uncertain.²⁵

Surgical Therapy

Primary repair is direct reconnection of the nerve immediately after injury. In an epineurial repair, the epineuriums of the separated nerve endings are sutured together using a microsuture (usually 8-0 or 10-0 Ethicon).¹⁹ Best results occur when the nerves are either purely sensory or purely motor and when the intraneural connective tissue component is small (this can vary from 22-80%^5,19 ) and the fascicles have been clearly aligned.

Sharp lacerations without loss of nerve substance or partial lacerations with proper alignment are good examples of injuries that benefit from epineurial repair. In a crushing or delayed repair requiring trimming of the nerve ends, group fascicular repair improves fascicular alignment without an excessive number of sutures. Excessive sutures add to scar tissue production. Individual fascicle repair is not practiced widely because it requires numerous sutures and because it is technically difficult.⁵

Secondary repairs are delayed repairs that may entail different strategies. Bones can be shortened to add length to a nerve. Nerve transposition across a flexed joint (eg, the ulnar nerve in the elbow) is another strategy for gauging nerve length in secondary repairs.⁵ These techniques can gain as much as an approximate 10% increase in available nerve length.⁵ However, within 3 weeks after injury, a nerve may lose as much as 8% of its length.⁵ Many surgeons prefer delayed suture to primary suture because this allows the wound to heal and it decreases the risk of infection. In addition, during a delayed repair, scarred ends of the nerve can be defined more accurately and trimmed back to normal fasciculi. The epineurial suture is more secure because the sheath has toughened.³ The suture of a severed nerve should not be delayed beyond 1 month.³

Neurolysis is performed on intraneural and extraneural scar tissue to release regenerating nerve fibers in the hope of improving functional recovery.⁶ Contaminated wounds, such as gunshot wounds and avulsions with severe tissue disruption, benefit from a secondary repair.⁶ Severely damaged nerves may require a nerve graft. For example, a graft would be necessary if, after resection of injured nerve ends (including neuroma), the defect could not be closed without tension.¹⁹

Studies show that sensation can return after nerve grafting.²⁶ The sural nerve is the criterion standard for nerve autografts because of a favorable ratio of axons to epineuriums.⁵ Loss of the sural nerve produces only a well-tolerated sensory loss on the lateral foot. Extensive research has focused on the use of allograft nerves to replace peripheral nerves that require a long nerve graft. Allografts can survive if the patient is immunosuppressed and if the nerve allograft is preserved to maintain cell viability. Immunosuppression can be discontinued when the nerve graft has been incorporated with an ingrowth of Schwann cells from the host nerve ends. Nevertheless, results from autograft use are slightly more favorable than allograft use.⁵

Artificial conduits have not proven to be as successful as conventional nerve autografts.⁵ Brain-derived neurotrophic factor (BDNF) and collagen tubulization have been used in an attempt to create a reliable artificial conduit for axonal regeneration.²⁷

Nerve or tendon transfers may be necessary for unrestorable or unsuccessful nerve repair. Brachial plexus injuries are not always reparable. In such cases, neurotizations or nerve transfers may offer a better functional outcome. The spinal accessory or long thoracic nerve can be grafted onto distal arm nerve trunks, with some improvement in elbow flexion.^3,28 When repair cannot or does not provide adequate results, planned tendon transfers can increase extremity function.³ Tendon transfers, such as the posterior tibialis tendon passing through the interosseous membrane, can add power to a foot with a peroneal deficiency.¹ Do not perform tendon transfers prior to 3 months after injury because early surgical exploration with nerve graft placement yields better results compared with primary tendon transfer.⁷

Preoperative Details

Preoperative details include determining the type of surgery to be performed and the time frame. For example, open injuries may require immediate surgery and closed injuries may require reduction (in cases of dislocations or fractures) and monitoring.⁴

Sunderland suggests 2 criteria that must be present before fascicular repair or interfascicular grafting is considered. The fascicular bundle must be large enough for suturing and must be sharply localized or sufficiently well defined so that it can be identified and mobilized for repair.³ Preoperative testing with SSEP, CT scan, EMG, and MRI has improved diagnostic accuracy.²⁸ The extent of surgical exploration is adapted to the reliability of the preoperative diagnosis.²⁸

Intraoperative Details

Intraoperative electrodiagnostic monitoring is important for assessing the functional integrity of motor and sensory peripheral nerves. The patient is draped to allow observation of the tested muscle groups. Intraoperative SSEPs and direct electrical stimulation can be used. Regional and local anesthetic blocks or tourniquets are avoided to facilitate intraoperative electrophysiological testing.⁴ Surgically resecting scar tissue may prevent pain and promote healing.⁴ Keeping the nerve ends moist is important.¹⁹ Ocular loupes are useful for lower magnification and wide-field dissections and are very helpful in preparing the ends of nerves and vessels for repair.⁹ The nerve can be protected during surgery by reducing tension through joint and limb manipulation and shielding with a blunt retractor to prevent iatrogenic injury.¹³

Surgical exploration with intraoperative nerve stimulation helps determine if neurolysis is the only intervention necessary.²³ In a group of patients in whom treatment failed and who underwent operation for isolated and combined axillary nerve injuries, twice as many neurolyses as nerve grafts were performed compared with a group of patients who had successful treatment.¹⁵

Postoperative Details

Grant et al (1999) do not advocate the traditional several weeks of immobilization.⁴ Patients should undergo regular physical therapy to maintain a range of movement and to optimize the recovery of motor function as muscle reinnervation occurs.^4,6 A short period to allow healing and adequate strength of the repair site is advised.⁴ Protect repairs by relaxed joint posturing for approximately 3 weeks.⁹ To prevent disruption of sutures at the repair site, the patient should avoid overzealous physical activity.⁴ In nerve transfers, the extremity is immobilized for 4 weeks after surgery, at which time physical therapy is initiated.²⁸ Postoperative clinical and electrodiagnostic examinations are performed every 3 months for the first 2 years after surgery and every 6 months thereafter.²⁸

Follow-up

Clinical outcome is documented by serial clinical examinations and electrodiagnostic studies.⁴ Axillary injuries constitute an important clinical problem that requires close clinical and electrophysiologic evaluation during the months after the injury.¹³ As a general rule, Grant et al (1999) suggested examining patients at 2 weeks, 6 weeks, 3 months, 6 months, 1 year, and then at yearly intervals if necessary and practical after surgery.⁴ Test and document range of movement and recovery of strength and sensation at each visit. Electrodiagnostic studies can help reveal early signs of muscle reinnervation, several months before clinically evident muscle contractions appear.⁴ After nerve transfer surgery, assess patients 3 years after surgery.²⁸ In most cases, maximal recovery requires as long as 24 months.²⁸ An advancing Tinel sign suggests, but does not prove, regeneration of the nerve.^3,18

Complications

Following acute nerve injury, various pain syndromes can develop.³ Plexus or root avulsions may produce burning dysesthesias and paresthesias.³ Painful neuromas and entrapment syndromes can arise at the site of injury and cause extreme local tenderness and pain.³ Partial nerve injuries of mixed motor and sensory function can lead to causalgia. Symptoms include severe hyperesthesia, hypersensitivity to cold or muscle activity, and increased pain in stressful situations.³ Paralysis can complicate nerve injury and sometimes cannot be repaired. If physical therapy is not instituted promptly after surgery, denervation can develop and result in muscle atrophy and fibrosis, joint stiffness, motor endplate atrophy, and trophic skin changes.⁶

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